ASABE publishes metric standard for LED horticultural lighting
By BizLED Bureau
Aug 9, 2017: The American Society of Agricultural and Biological Engineers (ASABE) has published the first in a series of three standards on horticultural lighting. The first standard focuses on definitions and descriptions of metrics.
ASABE has published the ANSI/ASABE S640 standard “Quantities and Units of Electromagnetic Radiation for Plants (Photosynthetic Organisms).”
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LED lighting has proved beneficial to horticulture, for vertical farms as well as supplemental under-cover applications in greenhouses. The standards are meant to provide a common language for characterizing LED-based systems to grow plants.
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The standards that characterize LED-based lighting for humans has been pending since a long time. Metrics like efficacy (lm/W) directly impact humans because lumen is based on human visual sensitivity. But these metrics do not have applicability for plant growth.
ASABE had begun work in 2015, and by 2016 the work has taken the shape of a three-part standards development. The first priority was to form the definition of metrics and a new plant biologically active radiation (PBAR) radiometric band that spans 280–800 nm. It covers the ultraviolet (UV) region below human visual sensitivity and the far-red region above.
The horticultural lighting sector has been using the metrics like photosynthetic photon flux (PPF) and photosynthetic photon flux density (PPFD). These are based on the photosynthetically active radiation (PAR) band from 400-700 nm. Now it is found that UV light is impacting plant morphology, particularly seed germination, flower induction, plant height, and leaf expansion. The new ASABE standard adds new metrics in these regions.